This research is of a twofold nature--to study both the static and dynamic properties of the biogenic monoamines. Detailed three-dimensional maps of the concentrations of norepinephrine (NE), dopamine (DA), 5-hydroxytryptamine (5-HT) and ascorbic acid (AA) in thalamus, frontal cortex and cingulate cortex will be developed by gridding coronal slices of brain tissue and analyzing each section by high performance liquid chromatography with electrochemical detection. Special emphasis will be placed on studying the DA distributions, since this has already shown surprising variability in rat thalamus. The possibility that this excessive variability among animals extends to rat frontal cortex will be especially examined. The unusual variability of DA innervation has significant implications in the current biological theories of schizophrenia. The technique of in vivo voltammetry will be used to measure the release of NE in rat thalamus elicited by peripheral somatosensory stimulation. While it is widely believed that NE is released and may modulate incoming sensory information in cortex and other brain regions, no proof of its in vivo release has been forthcoming. The use of a newly developed measurement which combines in vivo voltammetry (to measure biogenic amine release) and ion-selective micropipets (to measure extracellular fluxes of ions) will be applied to studying sensory processing in the rat thalamus. Some recently developed micro chemical probes will be used to develop rapid, sensitive sampling techniques for brain tissue which should be amenable to automation. Such systems could have widespread use in both brain and chemical assays.